Yes, his flip-flops have clearly hurt his standing with voters. In fact, any candidate or anyone who flip-flops back and forth on an issue, agreeing at first and then disagreeing with it, will hurt his or her political and societal standing. We cannot trust some who keeps changing his or her stance on an issue.
Trump believes in diversification. As in steal every candidate's stance on every issue so he can cover all of his bases. Trump has taken every stance imaginable on immigration, and he has pulled muscles pivoting twenty different directions. This is purely a sign of desperation and we're in the 8th inning of the campaign with his team down plenty.This is what makes Trump so dangerous, he has used the most divisive racist rhetoric in modern times when he felt it was beneficial to do so, if he was up in the polls he would be signing a whole different tune, this is the general election he sees majority of Americas is not buying what he is peddling so he diverts.
Donald Trump continues to flip-flop on many of his major campaign talking points. This flip-flopping will likely hurt his standing with voters. Much of the electorate does not believe Trump is qualified to be president. The fact that Trump cannot get his major campaign proposals straight means that many voters will not take his campaign seriously.
People like trump because he says and does what he wants and can back it up because he's rich. If anything his flip flops have helped him. As they show voters the rich can do whatever they want. Many voters also believe no matter how many flip flops he does, he will always be less of a lier than Hillary's.
One of the biggest revelations of the current electoral race in America is that the many "flip flops" or changes of opinion and policy from Donald Trump have, evidently, had little or no effect on his popular standing with the people or the extent with which they believe his words.